插入排序（算导2.1-2)

//============================================================================
// Name        : Insertion.cpp
// Author      : yojiaku
// Version     :
// Copyright   : 算法导论-插入排序简单实现（只有mian函数）-按非降序排列
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
using namespace std;

int main() {
	int num[] = {2, 3, 8, 7, 0};
	int key(0);
	int i(0);
	for(int j = 1; j < 5; j++){
		key = num[j];
		// insert num[j] into the sorted num[0, ..., j-1]
		i = j - 1;
		while(i >= 0 && num[i] < key){
			num[i+1] = num[i];
			i = i -1;
		}
		num[i+1] = key;
	}
	for(int j = 0; j < 5; j++){
		cout << num[j] << " ";
	}
	cout << endl;
	return 0;
}

 

运行结果：

8 7 3 2 0

伪代码：

INSERTION-SORT(A)
for j = 2 to A.length
	key = A[j]
	// insert A[j] into the sorted sequence A[1, …, j-1]
	I = j – 1
	while(i > 0 and A[i] < key)
		A[i+1] = A[i]
		I = I -1
	A[i+1] = key

 

//============================================================================
// Name        : Insertion.cpp
// Author      : yojiaku
// Version     :
// Copyright   : 算法导论-插入排序简单实现（只有mian函数）-按非升序排列
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
using namespace std;

int main() {
	int num[] = {8, 3, 8, 7, 0};
	int key(0);
	int i(0);
	for(int j = 1; j < 5; j++){
		key = num[j];
		// insert num[j] into the sorted num[0, ..., j-1]
		i = j - 1;
		while(i >= 0 && num[i] > key){
			num[i+1] = num[i];
			i = i -1;
		}
		num[i+1] = key;
	}
	for(int j = 0; j < 5; j++){
		cout << num[j] << " ";
	}
	cout << endl;
	return 0;
}

运行结果：

0 3 7 8 8

伪代码：

INSERTION-SORT(A)
for j = 2 to A.length
	key = A[j]
	// insert A[j] into the sorted sequence A[1, …, j-1]
	I = j – 1
	while(i > 0 and A[i] > key)
		A[i+1] = A[i]
		I = I -1
	A[i+1] = key

 

上面用超级简单的c++代码实现了插入排序，是用的静态数组，不太好，下面稍微改进了一下，用了vector，但是还是不是很好，我会持续改进的！

//============================================================================
// Name        : Insertion.cpp
// Author      : yojiaku
// Version     :
// Copyright   : 算法导论-插入排序简单实现（只有mian函数）-按非升序排列-use vector
// Description : Hello World in C++, Ansi-style
//============================================================================

#include <iostream>
#include <vector>
using namespace std;
using std::vector;

int main() {
	//int num[] = {8, 3, 8, 7, 0};
	vector<int> num;
	cout << "请输入大于或等于0的数字进行排序，输出小于0的数字默认输入结束" << endl;
	int temp;
	while(cin >> temp && temp >= 0){
		num.push_back(temp);
	}
	int length = num.size();
	cout << "一共有" << length << "个数字进行比较" << endl;
	int key(0);
	int i(0);
	for(int j = 1; j < length; j++){
		key = num[j];
		// insert num[j] into the sorted num[0, ..., j-1]
		i = j - 1;
		while(i >= 0 && num[i] > key){
			num[i+1] = num[i];
			i = i -1;
		}
		num[i+1] = key;
	}
	for(int j = 0; j < length; j++){
		cout << num[j] << " ";
	}
	cout << endl;
	return 0;
}

 

运行结果：

请输入大于或等于0的数字进行排序，输出小于0的数字默认输入结束

1 3 3 1 5 2 9 0

-1

一共有8个数字进行比较

0 1 1 2 3 3 5 9

上面这个是用了size()来确定vector的大小以及for循环的条件，在我没找到更好的办法时就先这样吧。